diff --git a/theme/boost/scss/moodle.scss b/theme/boost/scss/moodle.scss
index 0f3e54f8f82..0016c8283d4 100644
--- a/theme/boost/scss/moodle.scss
+++ b/theme/boost/scss/moodle.scss
@@ -4,9 +4,6 @@ $breadcrumb-divider-rtl: "◀" !default;
 // Specific overrides to make Bootstrap RTL.
 @import "moodle/bootstrap-rtl";
 
-// Specific SCSS to make some Bootstrap 5 syntax work with Moodle.
-@import "moodle/bs5-bridge";
-
 // Old Moodle stuff from base theme.
 // Massive, needs broken up.
 @import "moodle/variables";
diff --git a/theme/boost/scss/moodle/bs5-bridge.scss b/theme/boost/scss/moodle/bs5-bridge.scss
deleted file mode 100644
index d6b52524026..00000000000
--- a/theme/boost/scss/moodle/bs5-bridge.scss
+++ /dev/null
@@ -1,161 +0,0 @@
-/* Bootstrap 5 bridge classes */
-
-/*
- * These variables used to bridge the gap between Bootstrap 4 and Bootstrap 5 for
- * alert and list-group-item.
- */
-
-// Reduces the background color intensity by 80%. This is the definition in BS5.
-$alert-bg-scale: -80% !default;
-// Reduces the border color intensity by 70%. This is the definition in BS5.
-$alert-border-scale: -70% !default;
-// Increases the text color intensity by 50%. This is the definition in BS5.
-$alert-color-scale: 50% !default;
-
-/*
- * These function used to bridge the gap between Bootstrap 4 and Bootstrap 5 and
- * and will be located in __functions.scss in Bootstrap 5
- * This file should be removed as part of MDL-75669.
- */
-
-// Tint a color: mix a color with white based on the provided weight.
-@function tint-color($color, $weight) {
-    @return mix(white, $color, $weight);
-}
-
-// Shade a color: mix a color with black.
-// This function darkens a given color with black based on the provided weight.
-@function shade-color($color, $weight) {
-    @return mix(black, $color, $weight);
-}
-
-// Shade the color if the weight is positive, else tint it.
-@function shift-color($color, $weight) {
-    @return if($weight > 0, shade-color($color, $weight), tint-color($color, -$weight));
-}
-
-// Visually hidden mixins
-@mixin visually-hidden() {
-    @include sr-only();
-}
-
-@mixin visually-hidden-focusable() {
-    @include sr-only-focusable();
-}
-
-/* These classes are used to bridge the gap between Bootstrap 4 and Bootstrap 5. */
-/* This file should be removed as part of MDL-75669. */
-.g-0 {
-    @extend .no-gutters;
-}
-
-.btn-close {
-    @extend .close;
-}
-
-// Generate all spacer classes for all breakpoints for directions start and end.
-// ps-1 > pl-1, pe-1 > pr-1, me-sm-1 > ml-sm-1, ...
-@each $breakpoint in map-keys($grid-breakpoints) {
-    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
-    @each $prop, $abbrev in (margin: m, padding: p) {
-        @each $size, $length in $spacers {
-            .#{$abbrev}s#{$infix}-#{$size} {
-                @extend .#{$abbrev}l#{$infix}-#{$size};
-            }
-            .#{$abbrev}e#{$infix}-#{$size} {
-                @extend .#{$abbrev}r#{$infix}-#{$size};
-            }
-        }
-    }
-}
-
-// Generate all margin auto classes for all breakpoints for directions start and end.
-// ps-auto > pl-auto, pe-auto > pr-auto, me-sm-auto > ml-sm-auto, ...
-@each $breakpoint in map-keys($grid-breakpoints) {
-    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
-    .ms#{$infix}-auto {
-        @extend .ml#{$infix}-auto;
-    }
-    .me#{$infix}-auto {
-        @extend .mr#{$infix}-auto;
-    }
-}
-
-// Generate all float classes for all breakpoints for directions start and end.
-// float-start > float-left, float-sm-end > float-sm-right, ...
-@each $breakpoint in map-keys($grid-breakpoints) {
-    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
-    .float#{$infix}-start {
-        @extend .float#{$infix}-left;
-    }
-    .float#{$infix}-end {
-        @extend .float#{$infix}-right;
-    }
-}
-
-// Generate all text classes for all breakpoints for directions start and end.
-// text-start > text-left, text-sm-end > text-sm-right, ...
-@each $breakpoint in map-keys($grid-breakpoints) {
-    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
-    .text#{$infix}-start {
-        @extend .text#{$infix}-left;
-    }
-    .text#{$infix}-end {
-        @extend .text#{$infix}-right;
-    }
-}
-
-.border-start {
-    @extend .border-left;
-}
-.border-end {
-    @extend .border-right;
-}
-.border-start-0 {
-    @extend .border-left-0;
-}
-.border-end-0 {
-    @extend .border-right-0;
-}
-.rounded-start {
-    @extend .rounded-left;
-}
-.rounded-end {
-    @extend .rounded-right;
-}
-
-// Generate sized rounded classes.
-.rounded-1 {
-    @extend .rounded-sm;
-}
-.rounded-3 {
-    @extend .rounded-lg;
-}
-
-// Generate all font-weight and font-style classes.
-.fw-light {
-    @extend .font-weight-light;
-}
-.fw-lighter {
-    @extend .font-weight-lighter;
-}
-.fw-normal {
-    @extend .font-weight-normal;
-}
-.fw-bold {
-    @extend .font-weight-bold;
-}
-.fw-bolder {
-    @extend .font-weight-bolder;
-}
-.fst-italic {
-    @extend .font-italic;
-}
-
-// Generate visually-hidden classes.
-.visually-hidden {
-    @extend .sr-only;
-}
-.visually-hidden-focusable {
-    @extend .sr-only-focusable;
-}